1. Field of the Invention
The invention generally relates to writing or recording fluids on an aqueous basis and is particularly directed to writing or drawing ink which is essentially composed of coloring agents, binder, water and, in some instances, other additives.
2. Description of the Prior Art
German Offenlegungsschrift No. 2,136,055 discloses an ink or graphic dye suitable for inscribing film carriers by means of jet printers. The binder for the ink or dye as disclosed in this prior art publication is a resin of styrene and maleic acid anhydride or a carboxylated polyvinyl acetate and/or polyacrylic resin. The Offenlegungsschrift teaches that the primary reason for using such a binder is to facilitate contactless, damage-free inscribing of the carrier, particularly a film carrier or photographic negative.
According to German Auslegeschrift No. 2,837,158, drawing inks usually contain shellac or shellac-borax mixtures as binder. The Auslegeschrift proposes to replace these binders by polyvinyl pyrrolidone (PVP). In this manner, it is suggested that the application of the writing or drawing is obtained in such a state or form that it can be readily corrected.
Previously, drawing inks were predominantly produced with gum arabic, glue solution or blood serum as binder (see Roempp's Chemie Lexikon (Chemical Encyclopedia), 7th Edition, 1977, page 3710, left column).
German Offenlegungsschrift No. 2,132,324 discloses a writing or drawing ink of low viscosity, which contains polyvinyl pyrrolidone and a polyethylene oxide as water-soluble resin, in order to avoid spraying or blotting especially when such an ink is used in a recording mechanism or inking system and the recording element is moved rapidly in order to shift its position.
Within certain limits, the known writing fluids fulfill their particular, designated objectives. Generally, however, they have a high heat sensitivity, offer a limited possibility for using other solvents, have a relatively high viscosity and therefore a lower operating speed, tend to become brittle or have inadequate adhesion to the script carrier, especially to transparent papers or sheets, or are--especially if they contain natural resins or other natural products--susceptible to aging, so that the use of additional preservatives is required.